Re: [PATCH RFC 1/2] rhashtable: accept GFP flags in rhashtable_walk_init

[Thomas Graf]

On 02/28/16 at 08:06pm, Bob Copeland wrote:
> In certain cases, the 802.11 mesh pathtable code wants to
> iterate over all of the entries in the forwarding table from
> the receive path, which is inside an RCU read-side critical
> section.  Enable walks inside atomic sections by allowing
> GFP_ATOMIC allocations for the walker state.
> 
> Change all existing callsites to pass in GFP_KERNEL.
> 
> Cc: Thomas Graf 
> Cc: netdev@vger.kernel.org
> Signed-off-by: Bob Copeland 

rhashtable bits LGTM

Acked-by: Thomas Graf 

Re: [PATCH RFC 1/2] rhashtable: accept GFP flags in rhashtable_walk_init

[Bob Copeland]

On Tue, Mar 01, 2016 at 02:54:16PM +0100, Johannes Berg wrote:
> On Sun, 2016-02-28 at 20:06 -0500, Bob Copeland wrote:
> > In certain cases, the 802.11 mesh pathtable code wants to
> > iterate over all of the entries in the forwarding table from
> > the receive path, which is inside an RCU read-side critical
> > section.  Enable walks inside atomic sections by allowing
> > GFP_ATOMIC allocations for the walker state.
> > 
> > Change all existing callsites to pass in GFP_KERNEL.
> 
> Both look fine to me.
> 
> I see you have more patches for mesh, so this probably can't go through
> net-next tree directly.

Yeah, these two are on top of the other mesh path table changes.

So either both of these could go via mac80211-next or we could do the
1/2 in net-next and wait to apply 2/2 in mac80211-next.  Whatever works
for you guys.

-- 
Bob Copeland %% http://bobcopeland.com/

Re: [PATCH RFC 1/2] rhashtable: accept GFP flags in rhashtable_walk_init

[Johannes Berg]

On Sun, 2016-02-28 at 20:06 -0500, Bob Copeland wrote:
> In certain cases, the 802.11 mesh pathtable code wants to
> iterate over all of the entries in the forwarding table from
> the receive path, which is inside an RCU read-side critical
> section.  Enable walks inside atomic sections by allowing
> GFP_ATOMIC allocations for the walker state.
> 
> Change all existing callsites to pass in GFP_KERNEL.

Both look fine to me.

I see you have more patches for mesh, so this probably can't go through
net-next tree directly.

johannes

[PATCH RFC 1/2] rhashtable: accept GFP flags in rhashtable_walk_init

[Bob Copeland]

In certain cases, the 802.11 mesh pathtable code wants to
iterate over all of the entries in the forwarding table from
the receive path, which is inside an RCU read-side critical
section.  Enable walks inside atomic sections by allowing
GFP_ATOMIC allocations for the walker state.

Change all existing callsites to pass in GFP_KERNEL.

Cc: Thomas Graf 
Cc: netdev@vger.kernel.org
Signed-off-by: Bob Copeland 
---
 include/linux/rhashtable.h | 3 ++-
 lib/rhashtable.c   | 6 --
 net/ipv6/ila/ila_xlat.c| 3 ++-
 net/netfilter/nft_hash.c   | 4 ++--
 net/netlink/af_netlink.c   | 3 ++-
 net/sctp/proc.c| 3 ++-
 6 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index 63bd7601b6de..3eef0802a0cd 100644
--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -346,7 +346,8 @@ struct bucket_table *rhashtable_insert_slow(struct 
rhashtable *ht,
struct bucket_table *old_tbl);
 int rhashtable_insert_rehash(struct rhashtable *ht, struct bucket_table *tbl);
 
-int rhashtable_walk_init(struct rhashtable *ht, struct rhashtable_iter *iter);
+int rhashtable_walk_init(struct rhashtable *ht, struct rhashtable_iter *iter,
+gfp_t gfp);
 void rhashtable_walk_exit(struct rhashtable_iter *iter);
 int rhashtable_walk_start(struct rhashtable_iter *iter) __acquires(RCU);
 void *rhashtable_walk_next(struct rhashtable_iter *iter);
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index cc808707d1cf..5d845ffd7982 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -487,6 +487,7 @@ EXPORT_SYMBOL_GPL(rhashtable_insert_slow);
  * rhashtable_walk_init - Initialise an iterator
  * @ht:Table to walk over
  * @iter:  Hash table Iterator
+ * @gfp:   GFP flags for allocations
  *
  * This function prepares a hash table walk.
  *
@@ -504,14 +505,15 @@ EXPORT_SYMBOL_GPL(rhashtable_insert_slow);
  * You must call rhashtable_walk_exit if this function returns
  * successfully.
  */
-int rhashtable_walk_init(struct rhashtable *ht, struct rhashtable_iter *iter)
+int rhashtable_walk_init(struct rhashtable *ht, struct rhashtable_iter *iter,
+gfp_t gfp)
 {
iter->ht = ht;
iter->p = NULL;
iter->slot = 0;
iter->skip = 0;
 
-   iter->walker = kmalloc(sizeof(*iter->walker), GFP_KERNEL);
+   iter->walker = kmalloc(sizeof(*iter->walker), gfp);
if (!iter->walker)
return -ENOMEM;
 
diff --git a/net/ipv6/ila/ila_xlat.c b/net/ipv6/ila/ila_xlat.c
index 295ca29a23c3..0b03533453e4 100644
--- a/net/ipv6/ila/ila_xlat.c
+++ b/net/ipv6/ila/ila_xlat.c
@@ -501,7 +501,8 @@ static int ila_nl_dump_start(struct netlink_callback *cb)
struct ila_net *ilan = net_generic(net, ila_net_id);
struct ila_dump_iter *iter = (struct ila_dump_iter *)cb->args;
 
-   return rhashtable_walk_init(>rhash_table, >rhiter);
+   return rhashtable_walk_init(>rhash_table, >rhiter,
+   GFP_KERNEL);
 }
 
 static int ila_nl_dump_done(struct netlink_callback *cb)
diff --git a/net/netfilter/nft_hash.c b/net/netfilter/nft_hash.c
index 3f9d45d3d9b7..6fa016564f90 100644
--- a/net/netfilter/nft_hash.c
+++ b/net/netfilter/nft_hash.c
@@ -192,7 +192,7 @@ static void nft_hash_walk(const struct nft_ctx *ctx, const 
struct nft_set *set,
u8 genmask = nft_genmask_cur(read_pnet(>pnet));
int err;
 
-   err = rhashtable_walk_init(>ht, );
+   err = rhashtable_walk_init(>ht, , GFP_KERNEL);
iter->err = err;
if (err)
return;
@@ -248,7 +248,7 @@ static void nft_hash_gc(struct work_struct *work)
priv = container_of(work, struct nft_hash, gc_work.work);
set  = nft_set_container_of(priv);
 
-   err = rhashtable_walk_init(>ht, );
+   err = rhashtable_walk_init(>ht, , GFP_KERNEL);
if (err)
goto schedule;
 
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index c8416792cce0..6e0cbdeb21d3 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2335,7 +2335,8 @@ static int netlink_walk_start(struct nl_seq_iter *iter)
 {
int err;
 
-   err = rhashtable_walk_init(_table[iter->link].hash, >hti);
+   err = rhashtable_walk_init(_table[iter->link].hash, >hti,
+  GFP_KERNEL);
if (err) {
iter->link = MAX_LINKS;
return err;
diff --git a/net/sctp/proc.c b/net/sctp/proc.c
index cfc3c7101a38..c5991e5e5daf 100644
--- a/net/sctp/proc.c
+++ b/net/sctp/proc.c
@@ -319,7 +319,8 @@ static int sctp_transport_walk_start(struct seq_file *seq)
struct sctp_ht_iter *iter = seq->private;
int err;
 
-   err = rhashtable_walk_init(_transport_hashtable, >hti);
+   err = rhashtable_walk_init(_transport_hashtable, >hti,
+